A fuel injector for fuel injection systems of internal combustion engines is described in German Patent Application No. DE 103 60 330 A1. The fuel injector includes a valve needle, which interacts with a valve seat surface to form a seal seat, and an armature connected to the valve needle, to which a restoring spring is applied in a closing direction, and which interacts with a solenoid coil. The armature is situated in a recess of an outer pole of the magnetic circuit and has a collar, which is formed circumferentially on the armature having a triangular cross section. Seal-dependent hydraulic damping of the armature results due to this shape of the collar. The damping takes place with respect to the opening movement, while the closing movement takes place nearly unobstructed, so that the fuel injector may be closed rapidly.